Longitudinal contraction unit



Sept. 5, 1950 E. s. MATHl-:Rs

LONGITUDINAL CONTRACTION UNIT Filed Feb. 25. 1948 v e v .f ,s U w N NNN N RN Patented Sept. 5, 1950 LONGITUDINAL CONTRACTION UNIT Edward S. Mathers, Baltimore, Md., assignor to Highway Supply Corporation, Jessup, Md., a corporation of Maryland Application February 25, 1948, Serial No. 10,703

2 Claims.

This invention relates to road or pavement constructions and more particularly to contraction joint arrangements, such as those usually provided in concrete roadways in ordej` to promote the cracking or cleavage of the slabs along straight lines, and thus prevent irregular cracking which is not only unsightly but tends to fragmentize and deteriorate the slabs. These contraction structures are most commonly utilized along the longitudinal center lines of wide road slabs, while the conventional expansion joints usually embodying elastic material serve to divide the slabs transversely of the roadway.

The general object of the invention is the provision of a novel and improved contraction joint structure which is simple in construction and easy to transport and assemble. The novel structure is also relatively light in Weight and economical to manufacture, but at the same time sturdy and capable of accurately .dening the line of the jointl and also of tying together the adjacent slab sections and distributing the load between them.

In its preferred embodiment the invention contemplates the provision of an elongated relatively thin contraction strip and a series of chairs or supports therefor. The contraction strip is adapted to be embedded in the concrete in a vertical position, the strip preferably being of less height than the thickness of the slab and disposed wth its upper edge either liush With the top surface of the slab or slightly below that surface.

The chairs or supports each comprise a pair of spaced wickets which constitute, in effect, tie rods with downwardly projecting legs adapted to contact the sub-grade. The mid-points of the two bent tie rods are connected by a spacer rod or bar, which may be joined to the tie bars by Welding. At each of said Welded connections there is secured a U-shaped clip the spaced upwardly extending arms of which are adapted to receive the contraction plate or strip. The base of this U-shaped clip is preferably welded to both the transversely extending tie rod and the longitudinally extending spacer rod at the point of connection between the two.

In practice, the double or four-legged chairs or supports are aligned at intervals along the subgrade, the contraction plate or strip inserted in the clips, the feet of the tie rods appropriately anchored or spiked, and the concrete poured.

Other objects and features of novelty will be apparent from the following specication when read in connection with the accompanying drawings in which one embodiment of the invention is illustrated by way of example.

In the drawings:

Figure l is a view in longitudinal section of a road bed embodying the novel contraction assembly provided by the invention; i

Figure 2 is a transverse sectional View on an enlarged scale taken on line 2 2 of Figure 1; and v Figure 8 is a view in perspective of one of the contraction units employed in making the joint.

In the rst two figures of drawing the reference character A represents a concrete road bed which is shown in longitudinal section in Figure l and transverse section in Figure 2. The slabs of concrete comprising the road bed A rest upon the sub-grade B and the upper surface is cambered to provide a crown C from which it slopes very gradually to the shoulders of the road.

The elongated contraction strip or plate I0 extends longitudinally along the central vertical plane of the road bed A the strip being embedded therein and, in this particular embodiment, having its upper edge flush with the upper surface of .the road bed A. According to some practices, the contraction plates are embedded well within the slabs comprising the road bed and spaced from both the upper and lower surfaces. Such variations in positioning the contraction plate are within the purview of the present invention.

According to one of the purposes of the contraction structure, the road bed A is shown with a longitudinal crack I2 therein which is promoted by the strip I and occurs when the road bed has hardened and set, as is well known in the art.

The essential features of the present invention lie in the nature of the supporting means which is provided for the contraction plate or strip Ill and this means comprises a series of longitudinally spaced chairs or supporting units, one of which is illustrated in perspective in Figure 3 of the drawings. This unit, which is designated generally by the reference character D, comprises a pair of spaced inverted substantially U-shaped cross bars I5 which are provided with downwardly inclined legs I6 and the substantially horizontal outwardly turned feet I1. These bent bars or rods I5 also constitute tie rods which extend transversely of the contraction joint and serve to transfer stresses from one portion of the roadway slab to the other.

The tie rods I5 of each pair are connected in xed spaced relationship by means of the spacer bar or rod 20 which is connected at its ends with the intermediate points of the upper body portions of the tie rods I5. The spacer rods 2B are best connected to the tie rods by means of welding.

Secured adjacent the ends of the supports D are the U-shaped clips 25 which may comprise flat plates bent upon themselves to provide a pair of flanges spaced just far enough apart to snugly receive the contraction strip l0. The base or bight of each of 'the clips 25 may be secured 'to one end 'or the other of vthe chair D by welding. For example, the slip may be positioned as clearly shown in Figure 3 of the drawings with th'e greater portion of its length welded to the upper surface of the end of the spacer rod 20 and with the remaining portion thereof A'overlappin,g tl-'ie body portion of the tie rod I5 and securely welded thereto. This provides a strengthened junction of the parts of the chair at the adjacent ends thereof and also insures that the clips themselves are securely carried by the support. Obviously the clips 25 might be secured at any point along the spac'er ro'd 2D, but for the reasons just stated, it is preferred to fix them at the ends of the chair as shown.

It will be readily perceived that the two tie 4lods {Sand the spacer rod 20 provide a four-legged chair or support for the strip I0, and one which may be made expeditiously and economically, 1readily transported to the scene of construction, set in position upon the sub-grade, and readily assembled with the strip `beforep'ouring the road bed. The chairs may be lsecured upon the subrgrade by any suitable means, the anchor pins 28 being shown in Figure 2 of the drawings as effecting this purpose.

Various changes and modifications may be made in the embodiments illustrated herein without departing from the scope vof the invention as `dened by the following claims.

Having thus described the invention, what is 'claimed as new and desired 'to be secured by Letters -Patent is:

l. A 'contraction joint construction for concrete roadways or the like, comprising, in combination: a vertically disposed relatively thin elongated contraction strip Vadapted to be 'embedded 'edgewise in the concrete of the roadway at the desired line vof fracture; and a plurality of supports for said strip ea'cli comprising a chai-r which comprises a 'skeleton-like metal member substantially Hs-shaped iin plan and having four downwardly directed legs a-t the corners thereof adapted to rest upon the sub-grade Aof the ro'ad nlli bed; said member comprising a pair of spaced parallel inverted U-shaped tie rods having their ends bent downwardly to form said legs, a spacer rod extending between the intermediate portions of the two tie rods, lying in the horizontal plane of said portions and having its ends abutting said respective intermediate portions, the said ends of the spacer rod being respectively butt-welded to said intermediate portions, a U-shaped clip secured to the upper part of the support adjacent each end thereof, the lower bight portion of each clip bridging `the adjacent tie rod and the abutting end of the spacer rod and being welded to both the tie rod and the spacer rod, said clips removably receiving a portion of said elongated contraction strip.

2. As an article of manufacture, a supporting chair 'for contraction strips of concrete roadways comprising, in combination, a skeleton-like metal member substantially H-shaped in plan and having -four downwardly directed legs at the corners thereof adapted to-rest upon the sub-grade of the road bed; said member comprising a pair of spaced parallel -inverted U-shaped tie rods hav- `ing their ends bent downwardly lto form said legs, a spacer rod 'extending between the intermediate portions of the two tie rods, lying in the horizontal plane of said portions and having its ends abutting said respective intermediate portions, the said ends of the spacer rod being respectively butt-Welded to vsaid intermediate portions, a U- shaped clip secured to the upper part of the support adjacent each end thereof, the lower bight portion of each clip bridging the adjacent tie Yrod andthe abutting end of the spacer rod and being welded to both the tie rod and the spacer rod, said clips adapted to removably receive a portion of an elongated contraction strip.

EDWARD S. MATHERJS.

REFERENCES CITED The lvfollowing references are of record in the iile of this patent:

UNITED STATES PATENTS Nuinber Name Date 1,371,857 Calkins Mar, 1:5, 1'921 n1,863,115 Heltzel June 14, 1932 2,150,982 McFarland Mar. 21, 1'939 "la-'179,911 Wilmoth Nov. Y14, 193'9 2,242,610 Johnson May 20I 1941 

